The present invention relates to an apparatus for managing degree of compaction in a vibratory compacting vehicle.
As a prior art apparatus for managing degree of compaction in a vibratory compacting vehicle, one known apparatus is constructed such that the acceleration of the roll in the vertical directions, which occurs when the roll strikes the ground, is detected and utilized to manage the degree of compaction of the ground. Such acceleration information is indicated, for example, on an instrument panel provided at the driver seat. However, this prior art apparatus is complicated in structure because parts such as an acceleration sensor are arranged in the roll. Also, in the case of adjusting the traveling speed of the vehicle on the basis of the acceleration information, it is difficult for an immature operator to determine instantly whether the current traveling speed is corresponding to, or too fast or too slow against the optimum traveling speed at which the most efficient compaction is achieved, or how much is the difference between the current traveling speed and the optimum traveling speed.
In view of the above, International patent Application PCT/US96/16872 (published under WO97/15726) discloses an apparatus for providing an indication of compaction in a vibration compaction vehicle. The outline of the apparatus is described below with reference to FIG. 13.
As seen in FIG. 13, a first electric signal from a speed sensor 71 that senses the traveling speed of the vehicle is transmitted to means 72 for converting the first electric signal into a distance of longitudinal travel per unit time of the vehicle (electric signal-to-distance converter) and the converted electric signal is outputted to a vibratory impact amount calculator 73. A second electric signal from a vibration sensor 74 that senses the number of vibrations of the roll is transmitted to means 75 for converting the second electric signal into the number of vibratory impacts (number of vibrations) per unit time (electric signal-to-number of vibrations converter) and the converted electric signal is outputted to the vibratory impact amount calculator 73. The vibratory impact amount calculator 73 calculates these two electric signals, produces an electric signal corresponding to the number of vibrations transmitted per unit of longitudinal travel of the vehicle, and outputs the produced electric signal to an indicator 76 provided at the driver seat.
The indicator 76 is provided with scale markings of absolute value in relation to the number of vibrations transmitted per unit of longitudinal travel of the vehicle, so that with the indicating pointer 76a indicating the scale markings the operator realizes the number of vibrations transmitted per unit of longitudinal travel of the vehicle in the current travel. If the indicator 76 is provided with scale markings indicating the number of vibrations per foot and if the supervisor determines that the optimum number of vibrations per foot, at which the most efficient compaction is achieved, is xe2x80x9c10xe2x80x9d for the ground, the operator adjusts the traveling speed of the vehicle such that the indicating pointer 76a always points at xe2x80x9c10xe2x80x9d of the scale markings.
However, this apparatus has the following drawbacks. That is, since two sensors such as the speed sensor 71 and the vibration sensor 74 are required, the whole apparatus becomes complicated in structure. Further, since the value indicated on the indicator 76 represents the number of vibrations transmitted per unit of longitudinal travel of the vehicle, it is difficult for an immature operator to comprehend instantly the relation between the current traveling speed of the vehicle and the optimum traveling speed for the ground.
The value indicated on the indicator 76 represents the number of vibrations transmitted per unit of longitudinal travel of the vehicle, that is, an absolute value. The operator thus remembers the absolute value during the operation. However, the optimum number of vibrations transmitted per unit of longitudinal travel of the vehicle is different for each mixture condition of the ground materials, etc., and the operator has to comprehend absolute values for different mixture conditions, which is tedious and may cause a possibility in mixing up with different values by mistake during the operation. Especially, if the operation is carried out in the same work site over an extended time period, in most cases, a plurality of operators works by turns, which may cause a possibility in working with the use of different values unless the determined absolute value is informed thoroughly.
The present invention is made to overcome the aforementioned drawbacks and the purpose thereof is to provide an apparatus for managing degree of compaction in a vibratory compacting vehicle, whereby the operator readily comprehends the optimum traveling speed of the vehicle for each mixture condition of the ground materials.
According to a first aspect of the present invention, there is provided an apparatus for managing degree of compaction in a vibratory compacting vehicle having a roll to be vibrated comprising: a vehicle speed sensing means which senses a traveling speed of the vehicle; a vibration number setting means by which a number of vibrations of the roll transmitted per unit time is set; a reference vibration number setting means by which a reference number of vibrations of the roll transmitted per unit of longitudinal travel of the vehicle is set; a control means controlling electric signals outputted from the vehicle speed sensing means, the vibration number setting means, and the reference vibration number setting means, respectively; and an indicating means relatively and comparatively indicating, as a vehicle speed index value, magnitude relation of a current number of vibrations of the roll transmitted per unit of longitudinal travel of the vehicle relative to the reference number of vibrations of the roll transmitted per unit of longitudinal travel of the vehicle on the basis of an electric signal outputted from the control means.
This structure enables the operator to readily adjust the traveling speed of the vehicle without recognizing a specific numerical value of the reference number of vibrations.
Further, unlike prior art, the vibration sensor sensing the number of vibrations of the roll is not required, which makes it possible to reduce the number of manpower required for the assembly of the apparatus and provide an apparatus for managing degree of compaction in simple structure.
According to a second aspect of the invention, the control means of the aforementioned apparatus may include: a vibration number calculating section calculating an electric signal outputted from the vehicle speed sensing means and an electric signal outputted from the vibration number setting means to work out a current number of vibrations of the roll transmitted per unit of longitudinal travel of the vehicle; and a vibration number comparing section comparatively calculating the current number of vibrations of the roll transmitted per unit of longitudinal travel of the vehicle that is calculated by the vibration number calculating section and the reference number of vibrations of the roll transmitted per unit of longitudinal travel of the vehicle that is set by the reference vibration number setting means.
According to a third aspect of the invention, the control means of the aforementioned apparatus may include: a vehicle speed calculating section calculating an electric signal outputted from the vehicle speed sensing means to work out a current vehicle speed; a reference vehicle speed calculating section calculating an electric signal outputted from the vibration number setting means and an electric signal outputted from the reference vibration number setting means to work out a reference vehicle speed; and a vehicle speed comparing section comparatively calculating the current vehicle speed worked out by the vehicle speed calculating section and the reference vehicle speed worked out by the reference vehicle speed calculating section.
These structures enable the control means to be simple in structure, which makes it possible to provide an apparatus for managing degree of compaction at lower cost.
According to a fourth aspect of the invention, the aforementioned apparatus may further comprise a non-volatile memory which stores the reference number of vibrations of the roll transmitted per unit of longitudinal travel of the vehicle to be set by the reference vibration number setting means.
In this structure of the apparatus, there is no need to reset the reference number of vibrations on a daily basis before initiating the operation.
According to a fifth aspect of the invention, the aforementioned apparatus may further comprise an engine speed sensing means which directly or indirectly senses a number of revolutions of an engine mounted on the vehicle, and wherein said control means controls an electric signal outputted from the engine speed sensing means.
In this structure of the apparatus, vehicle information can be indicated accurately without errors on the indicating means throughout the whole engine speed bands.